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AGENCY:

ACTION:

SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to all EMBRAER Model EMB-120 series airplanes, that would have required replacing certain existing potentiometers with recently manufactured potentiometers, modifying the flexible couplers that attach the shafts of the potentiometers to the shafts of the primary flight controls, performing repetitive calibration tests of the potentiometers and obtaining repetitive readouts of the flight data recorder (FDR), and reporting the results to the FAA. This new action proposes initial and repetitive testing of the potentiometers to detect noisy signals and replacement of only those with noisy signals. The actions specified by this new proposed AD are intended to prevent the potentiometers that provide Start Printed Page 13240information on the positions of the primary flight controls to the FDR from transmitting noisy signals or becoming improperly calibrated, resulting in the transmission of incomplete or inaccurate data to the FDR. This lack of reliable data could hamper discovery of the unsafe condition which caused an accident or an incident and prevent the FAA from developing and mandating actions to prevent additional incidents or accidents caused by that same unsafe condition.

DATES:

Comments must be received by April 14, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-120-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-120-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.

For each issue, state what specific change to the proposed AD is being requested.

Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-120-AD.” The postcard will be date stamped and returned to the commenter.

Discussion

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR 39) to add an airworthiness directive (AD), applicable to all EMBRAER Model EMB-120 series airplanes, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on April 27, 2001 (66 FR 21107). That NPRM would have required replacing certain existing potentiometers with recently manufactured potentiometers, modifying the flexible couplers that attach the shafts of the potentiometers to the shafts of the primary flight controls, performing repetitive calibration tests of the potentiometers and obtaining repetitive readouts of the flight data recorder (FDR), and reporting the results to the FAA. Those actions were intended to prevent the potentiometers that provide information on the positions of the primary flight controls to the FDR from transmitting noisy signals or becoming improperly calibrated, resulting in the transmission of incomplete or inaccurate data to the FDR. This lack of reliable data could hamper discovery of the unsafe condition which caused an accident or an incident and prevent the FAA from developing and mandating actions to prevent additional incidents or accidents caused by that same unsafe condition.

Comments

Due consideration has been given to the comments received in response to the original NPRM.

Request to Change Applicability

One commenter requests that the applicability of the NPRM be changed from “all Model EMB-120 series airplanes” to “All Model EMB-120 series airplanes with a Flight Data Recorder installed or required by the Federal Aviation Regulations, certificated in any category.” The commenter points out that some Model EMB-120 series airplanes have been converted from passenger operation to freighter operation and, therefore, are no longer required to operate with FDRs. The FAA agrees and has changed this AD so that it applies to “Model EMB-120 series airplanes which are required by 14 CFR 135 to operate with a flight data recorder (FDR), certificated in any category.”

Request To Change Requirement to Replace All In-service Potentiometers

Three commenters request that the proposed replacement of all in-service potentiometers with potentiometers manufactured less than 12 months ago be changed. The commenters suggest instead that a download of the FDR testing data be performed to identify potentiometers with noisy signals and that only those potentiometers should be replaced.

The FAA agrees. EMBRAER has developed a procedure for determining whether or not a potentiometer has a noisy signal. That procedure has been incorporated into Section 31-30-00 of the EMBRAER Model EMB-120 Airplane Maintenance Manual (AMM), dated April 10, 2002. Accordingly, we have revised paragraphs (a), (b), and (c) of this supplemental NPRM to require testing of the potentiometers and replacement of those with noisy signals.

Request To Change the Interval for Repetitive Calibration and Readout

The same three commenters request that the interval for the repetitive testing of potentiometers be extended from 6 Start Printed Page 13241months to 12 months. The commenters state that the current EMBRAER EMB-120 Maintenance Review Board (MRB) requirements are for a yearly calibration and download test.

The FAA agrees. We find that the new procedure specified in the AMM will detect potentiometers with noisy signals and, thus, agree that the current MRB requirements for a yearly download are sufficient. We have changed the language of this proposed AD accordingly.

Request To Delete Requirement for Modification of the Flexible Couplers

One commenter requests that the FAA drop the proposed requirement to add locktite to the flexible coupler attachment screws to prevent loosening of the attachment screws. The commenter states that a screw which is properly installed and torqued should never come loose.

The FAA does not agree. We have had multiple reports of couplers coming loose and shifting the calibration; such a shift in calibration would not be discovered until the next readout of the FDR. Accordingly, no such change has been made to this proposed AD.

Request To Delete Reporting Requirement

One commenter requests that the proposed requirement to report results of the calibration test and readout be deleted. The commenter states that the requirement is unnecessary and imposes a hardship on operators.

The FAA agrees in part. We have dropped the reporting requirement in this AD, because we find that EMBRAER's procedure for detecting potentiometers with noisy signals will detect them and, therefore, reporting the results to the FAA, as proposed in the NPRM, is not necessary. Therefore, we have deleted the reporting requirement.

Request To Allow Use of Revised Issue of Service Bulletin

One commenter asks that use of EMBRAER Service Bulletin 120-31-0038, Change 02, dated June 25, 1998, be allowed in addition to the original issue, dated February 22, 1997. The commenter indicates that there is no difference in technical content between the original issue and Change 02 of the service bulletin. The FAA concurs and has revised the language of this proposed AD accordingly.

Conclusion

Since these changes expand the scope of the originally proposed rule, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for public comment.

Cost Impact

The FAA estimates that 250 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 3 work hours to perform the noise check of the potentiometers and obtain a readout of the FDR, that it would take approximately 1 work hour to apply adhesive to the flexible couplers, and that the average labor rate is $60 per work hour. The cost impact of the proposed AD on U.S. operators for the initial or repetitive testing of an airplane is as shown on the following table:

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket at the location provided under the caption ADDRESSES.

Applicability: Model EMB-120 series airplanes which are required by 14 CFR 135 to operate with a flight data recorder (FDR), certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or Start Printed Page 13242repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent the potentiometers that provide information on the positions of the primary flight controls to the FDR from transmitting noisy signals or becoming improperly calibrated, resulting in the transmission of incomplete or inaccurate data to the FDR, accomplish the following:

Initial Testing of Potentiometers

(a) Within 6 months after the effective date of this AD: Adjust the potentiometers to the ailerons, elevators, and rudder; perform a noise check of the potentiometers; and obtain a readout of the FDR, in accordance with Section 31-30-00 of the EMBRAER EMB-120 Airplane Maintenance Manual, dated April 10, 2002.

Repetitive Testing of Potentiometers

(b) Repeat the noise check of the potentiometers and obtain a readout of the FDR, as required by paragraph (a) of this AD, at intervals not to exceed 12 months.

Replacement of Potentiometers

(c) If any readout of the FDR, conducted in accordance with paragraphs (a) or (b) of this AD, indicates a potentiometer with a noisy signal: Within 20 days after obtaining the readout, replace the potentiometer in accordance with Section 31-30-05 of EMBRAER EMB-120 Airplane Maintenance Manual, dated July 17, 1998, with one that has a date of manufacture no greater than 12 months from the date of installation.

Modification of Flexible Coupler

(d) Prior to further flight, after the accomplishment of paragraph (a) of this AD: Apply locktite adhesive over the threads of the screws of the flexible couplers that attach the shafts of the potentiometers to the shafts of the primary flight controls, in accordance with EMBRAER Service Bulletin 120-31-0038, original issue, dated February 22, 1997; or Change 02, dated June 25, 1998.

Alternative Methods of Compliance

(e) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, International Branch, ANM-116, Transport Airplane Directorate, FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

Special Flight Permits

(f) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Note 3:

The subject of this AD is addressed in Brazilian airworthiness directive 97-08-01, dated August 29, 1997.